The history of glial cells is virtually ignored in comparison to that of neurons. Of the recent books examining the origins of glia, the famous Neuroglia by Kettenmann and Ransom, second edition (2005) has a lovely chapter written on the topic. A second book by Verkhratsky and Butt Glial Neurobiology (2007) has an authoritative introductory chapter on the origin of the word glia among other material. A third book by Webster and Astrm Gliogenesis: Historical Perspectives 1839-1985 (2009) ending in 1985 does not comprehend the recent role of glial cells, while its history roots in the 19th century are quite succinct, reduced to one paragraph per glial cell type. A fourth book by Fields The other brain: From Dementia to Schizophrenia, How New Discoveries about the Brain Are Revolutionizing Medicine and Science (2009), presents recent developments on glial biology without providing substantial historical content. The aforementioned books are merely the tip of the iceberg. This application requests funds to write a thorough historical account focusing exclusively on glia, organized at the cellular level, and presenting an updated function of the different glial cell types interacting with neurons. The ambitious aim of this book is to bridge th historical roots with the present knowledge on Glia to guide the reader through the jungle of the current literature. The concept underlying the book is the enormous progress of knowledge regarding the function of glial cells. 150 years ago, glial cells were initially viewed through the reductionist concept of 'glue' between neurons. Their concept has evolved during the course of the 20th century as auxiliary cells (ancillary - maid) of the nobler neuron. Now, glial cells are considered almost as important as neurons because of their involvement in modulating synaptic transmission, shaping the central nervous system architecture, assuring the basic survival of neurons... The book aims to retrace the change of concepts of glia, and reach a higher view of the cellular integration in the nervous system between neurons and the several glial cell types. The recent explosion of knowledge is challenging to comprehend the whole picture of the role of glia in the nervous system. It will give an historical perspective on how our understanding of the cells of the nervous system has advanced, and will lead to new insights as to how further advances can be made. No neurological disease can be understood without this integrated concept.